Real-time air sampling and analysis especially to detect toxic or lethal constituents is a challenging problem. The sampling must be fast to prevent injury or even loss of life yet must be sure in order to prevent false positives which could trigger false alarms resulting in huge unnecessary displacement of people and equipment. Measuring ultraviolet (UV) fluorescence is one technique that is sensitive but is not highly accurate. Infrared (IR) absorbance is another method which is more accurate but not so fast. IR spectroscopy has greater capability to discriminate against normally occurring background clutter that sets off UV fluorescence detectors. In addition to speed and accuracy of detection continuous monitoring is also often desirable or required.